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Dial In Your 90-98 Mazda Miata NA8C/NB8C Ride and Handling
The Tein Street Advance Z coilover kit (GSM64-9USS2) gives 90-98 Mazda Miata NA8C/NB8C owners a full-length adjustable suspension platform built around a twin-tube damper for a comfortable ride that still tightens up when the road gets twisty. Uses the vehicle's OE upper mounts (not included). Twin-tube damper system delivers a longer stroke and smaller repulsive force for high ride comfort, smooth low-speed behavior, and stable high-speed control. Ride height is adjustable via the lower spring seat. A sealed structure (narrowed shell pipe top, oil/gas injected, crimped seal) keeps cost efficient without sacrificing quality. An optimal dust boot protects the piston rod (some vehicles use OE dust boots). Street Advance Z adds a damping force adjustment dial so the driver can fine-tune compression and rebound feel for the road or track.
Key Features
- GSM64-9USS2 coilover kit built on a twin-tube damper for long stroke travel and a comfortable ride
- Damping force adjustment dial for on-the-fly ride feel tuning
- Full-length ride height adjustment via the lower spring seat
- No-Sag Spring made from cold-formed SAE9254 steel for long-term ride height retention
- High-performance damper oil rated for consistent street and spirited driving use
- TEIN-Green two-layer powder coating and ZTP-coated adjustment threads resist corrosion
- EDFC-compatible on applicable vehicles for in-cabin damping adjustment
Fitment Table
| Year Range | Make | Model | Trim |
|---|---|---|---|
| 1999 | Mazda | Miata | 10th Anniversary |
| 1990-1997 | Mazda | Miata | Base |
| 1999-2005 | Mazda | Miata | Base |
| 1993 | Mazda | Miata | LE |
| 2000-2005 | Mazda | Miata | LS |
| 1994-1997 | Mazda | Miata | M Edition |
| 2004-2005 | Mazda | Miata | Mazdaspeed |
| 1991 | Mazda | Miata | SE |
| 2000-2003 | Mazda | Miata | SE |
| 2003 | Mazda | Miata | Shinsen |
| 1997 | Mazda | Miata | STO |
Specifications
| Detail | Value |
|---|---|
| MPN | GSM64-9USS2 |
| Brand | Tein |
| Series | Street Advance Z |
| Damper Type | Twin-tube, damping force adjustable |
| Ride Height Adjustment | Full-length, via lower spring seat |
| Spring Type | No-Sag Spring, cold-formed SAE9254 steel |
| EDFC Compatible | Yes, on applicable vehicles |
| Condition | New |
What's Included
- 4x GSM64-9USS2 pre-assembled damper and spring units (front and rear)
- Ride height adjustment wrenches
- Installation instruction manual
- Damping force adjustment tool
About Tein
Tein has engineered coilover suspension in Japan for decades, and the GSM64-9USS2 Street Advance Z continues that lineage with a sealed, cost-efficient damper platform that does not compromise on ride quality or durability. The No-Sag Spring is cold-formed from SAE9254 steel with a minimum tensile strength of 200 kgf/mm2, resisting sag over time. Its durable powder coating resists peeling and flaking. The high-performance damper oil holds a stable viscosity across temperature ranges, resists foaming and cavitation, and tolerates heat, making it well suited for spirited street driving. TEIN-Green powder coating uses a patented two-layer, one-bake method (Japanese patent 4347712) with no harmful solvents. ZTP coating on the ride-height adjustment thread resists abrasion and corrosion to help prevent rust-seizure. Tein backs its coilovers with manufacturer-supported quality standards.
Related Parts
- Tein 12-13 Honda Civic Si (FB6/FG4) Street Advance Z Coilovers
- Tein 2016+ Honda Civic (FC2) Street Advance Z Coilovers
- Tein 87-92 Toyota Supra (MA70L) Street Advance Z Coilovers
FAQ
What is the GSM64-9USS2?The GSM64-9USS2 is a Tein Street Advance Z coilover kit designed for 90-98 Mazda Miata NA8C/NB8C. It replaces the factory shocks and springs with a twin-tube, damping-adjustable coilover system while reusing the OE upper mounts.
Is the damping force adjustable?Yes. The Street Advance Z includes a damping force adjustment dial so you can tune compression and rebound feel for street or spirited driving.
Can I lower my vehicle with this kit?Yes, the GSM64-9USS2 allows full-length ride height adjustment through the lower spring seat, independent of spring preload.
Does this kit work with EDFC controllers?It is EDFC-compatible on applicable vehicles, letting you adjust damping from inside the cabin. Compatibility should be confirmed for your specific chassis.
Are the factory upper mounts reused?Yes, the GSM64-9USS2 is designed to use the vehicle's OE upper mounts, which are not included in the kit.
What spring technology does this kit use?It uses Tein's No-Sag Spring, cold-formed from SAE9254 steel for high tensile strength and long-term sag resistance.
Is this kit suitable for daily driving?Yes, the GSM64-9USS2 twin-tube design is tuned for street comfort at low speed with stable control at higher speeds, making it a good daily-driver-friendly coilover.
What finish protects the coilovers from rust?Tein applies its patented TEIN-Green two-layer powder coating along with ZTP coating on the adjustment threads to resist corrosion and rust-seizure.
Install Instructions
- Raise and safely support the vehicle, then remove the wheel at each corner.
- Disconnect the factory shock and spring assembly, transferring the OE upper mount to the GSM64-9USS2 damper.
- Install the front and rear damper units, torquing all mounting hardware to factory specifications.
- Set the ride height at each corner using the lower spring seat, keeping the vehicle level side to side.
- Set the damping force dial to your preferred setting on each damper.
- Reinstall the wheels and lower the vehicle, then have an alignment performed before regular driving.
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